43681691 has 2 divisors, whose sum is σ = 43681692. Its totient is φ = 43681690.

The previous prime is 43681661. The next prime is 43681709. The reversal of 43681691 is 19618634.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-43681691 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (43681661) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 21840845 + 21840846.

It is an arithmetic number, because the mean of its divisors is an integer number (21840846).

Almost surely, 2^43681691 is an apocalyptic number.

43681691 is a deficient number, since it is larger than the sum of its proper divisors (1).

43681691 is an equidigital number, since it uses as much as digits as its factorization.

43681691 is an evil number, because the sum of its binary digits is even.

The product of its digits is 31104, while the sum is 38.

The square root of 43681691 is about 6609.2125854749. The cubic root of 43681691 is about 352.1814529126.

The spelling of 43681691 in words is "forty-three million, six hundred eighty-one thousand, six hundred ninety-one".